Marine propeller

ABSTRACT

A hub having an enlarged midsection and tapered forward and rearward portions is adapted to be attached to a propeller drive shaft. A plurality of outwardly extending arm members support a plurality of curved blades in a spaced-apart manner from the hub. The blades are positioned for squeezing water inwardly toward the rotational axis of the propeller during rotation of the propeller for increasing the water pressure adjacent the rearward portion of the hub for producing a desired forward thrust for the propeller.

United States Patent [72] Inventor Alberto Angel 8606 Morley, Houston,Tex. 77017 [21] App1.No. 841,345 [22] Filed July 14, 1969 [45] PatentedSept. 28, 1971 [541 MARINE PROPELLER 8 Claims, 4 Drawing Figs.

[52] U.S.C1 416/179, 416/236, 416/242 [51] Int. Cl B63h1/16 [50] Fieldoisearch 416/179,

[56] References Cited UNITED STATES PATENTS 3,504,990 4/1970 Sugden416/211 X FOREIGN PATENTS 15,012 8/1911 Denmark 416/180 99,797 9/1897Germany..... 416/210 5,294 1913 Great Britain 416/210 PrimaryExaminer-Everette A. Powell, Jr. AttorneysRichard E. Bee, Giles C.Clegg, Jr. and Jack A.

Kanz

MARINE PROPELLER BACKGROUND OF THE INVENTION This invention relates tomarine propellers for propelling boats, ships and other types of marinevessels through water.

As is known, present day marine propellers are not lpercent efficient.All of the power applied to the propeller drive shaft is not convertedinto forward movement of the boat.

Various advantages could be realized through the use of a more etiicientpropeller. The rate of fuel consumption for a given operation could bereduced. The speed of the vessel could be increased. The overalldiameter of the propeller could be reduced. A motor having a lowermaximum power rating could be used. Or a combination of these advantagescould be realized.

As is further known, every present day propeller has a definite upperlimit as to the rate at which it can be rotated. If this limit isexceeded, then cavitation eflects occur. Such effects can becomesufficiently violent to cause damage to the propeller and the mechanismsdriving same.

A marine propeller capable of operating at higher revolution rates thanpresent day propellers would offer various advantages. For the case oflarger oceangoing type boats and ships, for example, it would enable amore direct connection of the propeller to the high speed turbinescommonly used, thus providing a further improvement in overallefiiciency.

SUMMARY OF THE INVENTIOn It is an object of the invention, therefore, toprovide a new and improved marine propeller of increased eficiency.

It is another object of the invention to provide a new and improvedmarine propeller capable of operating at a higher number of revolutionsper minute with reduced vibration effects.

In accordance with the invention, a marine propeller comprises hub meanshaving an enlarged midsection and tampered forward and rearwardportions. The propeller also includes means for coupling the hub meansto the marine vessel to be propelled so that water may freely flow overthe hub means from the forward end to the rearward end thereof. Thepropeller further includes blade means spaced laterally of the rearwardportion of the hub means and means for rotating the blade means aroundan axis coaxial with the longitudinal axis of the hub means. The blademeans are shaped to cause an inward squeezing of the water as it flowspast the rearward portion of the hub means for increasing the waterpressure on the rearward portion of the hub means.

For a better understanding of the present invention, together with otherand further objects and features thereof, reference is bad to thefollowing description taken in connection with the accompanying drawing,the scope of the invention being pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawing:

FIG. 1 is a perspective view of a first embodiment of a marine propellerconstructed in accordance with the present invention;

FIG. 2 is a rear elevational view of the FIG. 1 propeller;

FIG. is a cross-sectional plan view taken along section line 3-3 of FIG.2; and

FIG. 4 is a rear elevational view of a second embodiment of a marinepropeller constructed in accordance with the present invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to FIGS. 1-3, thereare shown various views of a first embodiment of a marine propellerconstructed in accordance with the present invention. This embodimentincludes a hub adapted to be attached to a propeller drive shaft 11,which drive shaft 11 is connected to an appropriate motor or turbineunit (not shown) located aboard the ship to be propelled. Shaft 11rotates in the counterclockwise direction as viewed from the hub end inFIG. 1. Hub 10 is provided with an appropriate interior receptacle orsocket for receiving the end of the shaft 11. Appropriate elements suchas keys, keyways, retaining pins and the like are provided for fasteningthe hub 10 to the shaft 11 and for transferring the rotary motion ofshafl 11 to the hub 10. As best seen in FIG. 3, the hub 10 includes anenlarged midsection 12 and tapered forward and rearward portions 13 and14. Such forward and rearward portions 13 and 14 are of generallyconical shape with the axes of the cones being in line with one anotherand with the longitudinal or rotational axis of the propeller shaft 1 1.These cones are of different altitudes or axial dimensions with thealtitude of the forward cone 13 being the greater.

Disposed about the hub 10 are a plurality of curved blades 15, 16, 17and 18 which, as indicated in FIG. 2, are spaced apart from the hub 10and encircle the hub 10 in an overlapping manner. Each of the blades15-18 is in the form of a curved plate. For the present example, thecurvature of each blade as viewed in the edgewise manner of FIG. 2 isintended to correspond to a potion of a spiral type curve. Moreparticularly, it is intended to correspond to a portion of an involuteof a circle. As indicated in FIG. 3, the blades 15-18 encircle therearward portion 14 of the hub 10. The concave sides 15a-18a of theblades 15-18 face the hub 10 and the blades are positioned so that theirleading rotational edges 15b-18b are at a greater radial distance fromthe longitudinal center axis of the hub 10 than are their trailingrotational edges -180. As indicated in FIG. 2, the thickness of eachblade is greatest at its trailing rotational edge and decreases to arelatively thin knife edge like dimension at its leading rotationaledge.

The curved blades 15-18 are supported from the hub 10 by means ofsupport means represented in the present embodiment by a plurality ofarm members 21, 22, 23 and 24 which extend outward from the hub 10.These arm members 21-24 are attached to the hub 10 immediately ahead ofthe maximum diameter midsection line 12. As indicated in FIG. 3, thesearm members 21-24 are attached to the forward portions of the blades15-18. Each of the arm members 21-24 has attached thereto at anintermediate point the trailing rotational edge of one of the blades andat a greater radial distance a more leading rotational portion of asecond of the blades, such leading portion being near the leadingrotational edge of such second blade. As indicated in FIG. 1 for thecase of the blade 16, a recess 16d is formed in the blade 16 near thetrailing rotational edge for enabling passage of the arm member 21 tothe more distant portion of the overlapping blade 15. Similar recessesare provided in the other curved blades 15, 17 and 18.

As indicated in FIG. 3 for the arm member 24, the arm members 21-24 areprovided with a tapered cross-sectional shape and are cocked at an angleso that one of the tapered edges is nearer the front of the hub 10 thanis the other. This angle is such that when the propeller rotates the armmembers 21-24 also function like small propeller blades and, as such,serve to urge movement of the water in the rearward direction The mainfunction of the arm members 21-24 is, however, to support the primaryblades 15-18, the propeller action provided by such arm members 21-24being more in the nature of making the most of structures that areneeded for other purposes.

In operation, the curved blades 15-18 function to urge or squeeze thewater inwardly against the tapered rearward portion 14 of the hub 10during rotation of such blades 15-18. The sloping shape of this rearwardportion 14 serves to deflect the inwardly directed hydraulic flow in arearwardly direction and thus out the back end of the propellerassembly. The tapered shape of the forward portion 13 of the hub 10functions to direct the water entering the propeller assembly from theforward direction in an outwardly direction toward the curved blades15-18, from whence it is squeezed back in toward the rearward portion 14of the hub 10. Thus, the shape of both the forward portion 13 and therearward portion 14 are important in organizing the flow of the waterthrough the propeller assembly.

While it is convenient to think in terms of movement or flow of thewater, this tends to overlook the primary significance of the presentinvention. The more significant aspect of the matter is that thesqueezing of the water inwardly causes a very substantial increase inthe water pressure in the center portion of the region which is boundedby the curved blades 15-18. As is known from established hydraulicprinciples, this pressure is transmitted equally in all directions. As aconsequence, it reacts against the rearward portion 14 of the hub andthe rearward sides of the arm members 21-24 to produce the desiredforward thrust on the propeller shaft 11 for propelling the boat or shipthrough the water.

A conventional propeller operates more in the manner of a screw. Theblades of the convention propeller engage the water and produce a directthrust thereon which pushes the water in the rearward direction. Withthe present propeller, on the other hand, the primary blades 15-18 arenot engaged in such a rearward pushing of the water. instead, theyfunction to squeeze the water to increase the water pressure on the backside of the propeller hub. As a consequence, the buildup of a vacuumcondition on the forward side of the propeller assembly does not occurnearly so readily nor to the same extent as with a conventionalpropeller. Thus, the present propeller may operate at a considerablyhigher number of revolutions per minute before the cavitation point isreached.

Referring to FIG. 4, there is shown a rear elevational view of a secondembodiment of a propeller constructed in accordance with the presentinvention. The propeller that FIG. 4 includes six curved blades 30 whichare mounted in a spacedapart manner about a central hub 31 by means ofsix arm members 32. The hub 31 is provided with tapered forward andrearward portions in the same manner as for the hub 10 of the firstembodiment. The arm members 32 of FIG. 4 extend radially only to thetrailing rotational edges of diflerent ones of the curved blade 30.Additional support for the blades 30 is provided by a circular supportring 33 which is attached to the forward portions of the blades 30 at agreater radial distance than the extremities of the arm members 32. Asin the earlier embodiment, the blades 30 function to increase the waterpressure adjacent the sloping rearward portion of the hub 31 forpurposes of producing the desired forward thrust on the propeller shaft.

Propellers constructed in accordance with the present invention may beused with either inboard or outboard type motors. For larger size boatsor ships, two or more such propellers may be used on a given boat orship. Also, the pressure increasing curved blades of the presentinvention may, if desired, be used in combination with conventionalpropeller blades.

A propeller constructed in accordance with the present invention canvery readily provide a 10 percent improvement in efficiency as comparedwith a conventional propeller of the same overall diameter. With theexercise of proper care, the improvement can be more on the order ofpercent.

While there has been described what are at present considered to bepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is, therefore,intended to cover all such changes and modifications as fall within thetrue spirit and scope of the invention. What is claimed is: l. A marinepropeller comprising: hub means having an enlarged midsection andtapered forward and rearward portions; means for coupling the hub meansto the marine vessel to be propelled so that water may freely flow overthe hub means from the forward end to the rearward end thereof; blademeans spaced laterally of the rearward portion of the hub means; meansfor rotating the blade means around an axis coaxial with thelongitudinal axis of the hub means; and the blade means being shaped tocause an inward squeezing of the water as it flows past the rearwardportion of the hub means for increasing the water pressure on therearward portion of the hub means.

2. A marine propeller comprising:

a hub having an enlarged midsection and tapered forward and rearwardportions;

a propeller shaft for coupling the hub to the marine vemel to bepropelled and for spacing the hub apart from the hull of the vessel sothat water may freely flow over the hub from the forward end to therearward end thereof;

a plurality of curved blades;

and support means for spacing the blades laterally of the rearwardportion of the hub with the concave sides of the blades facing the huband positioned for squeezing water inwardly toward the rearward portionof the hub during rotation of the propeller.

3. A marine propeller in accordance with claim 2 wherein the shape ofthe hub corresponds to a pair of conical forms having a common base andpointing in opposite directions.

4. A marine propeller in accordance with claim 2 wherein the curvatureof each blade corresponds to a portion of a spiral.

5. A marine propeller in accordance with claim 2 wherein the supportmeans comprises a plurality of angularly spaced arm members which extendoutwardly from the hub.

6. A marine propeller in accordance with clam 5 wherein the arm membersare attached to forward portions of the curved blades.

7. A marine propeller in accordance with claim 6 wherein the arm membersare cocked at an angle so as to urge movement of water in the rearwarddirection.

8. A marine propeller in accordance with claim 2 wherein:

the shape of the hub corresponds to a pair of conical forms having acommon base and pointing in opposite directions;

each blade is in the form of a curved plate;

the blades are positioned to encircle the rearward portion of the hub inan overlapping manner;

and the support means comprise a plurality of angularly spaced armmembers which extend outwardly from the hub and are attached to forwardportions of the blades.

1. A marine propeller comprising: hub means having an enlargedmidsection and tapered forward and rearward portions; means for couplingthe hub means to the marine vessel to be propelled so that water mayfreely flow over the hub means from the forward end to the rearward endthereof; blade means spaced laterally of the rearward portion of the hubmeans; means for rotating the blade means around an axis coaxial withthe longitudinal axis of the hub means; and the blade means being shapedto cause an inward squeezing of the water as it flows past the rearwardportion of the hub means for increasing the water pressure on therearward portion of the hub means.
 2. A marine propeller comprising: ahub having an enlarged midsection and tapered forward and rearwardportions; a propeller shaft for coupling the hub to the marine vessel tobe propelled and for spacing the hub apart from the hull of the vesselso that water may freely flow over the hub from the forward end to therearward end thereof; a plurality of curved blades; and support meansfor spacing the blades laterally of the rearward portion of the hub withthe concave sides of the blades facing the hub and positioned forsqueezing water inwardly toward the rearward portion of the hub duringrotation of the propeller.
 3. A marine propeller in accordance withclaim 2 wherein the shape of the hub corresponds to a pair of conicalforms having a common base and pointing in opposite directions.
 4. Amarine propeller in accordance with claim 2 wherein the curvature ofeach blade corresponds to a portion of a spiral.
 5. A marine propellerin accordance with claim 2 wherein the support means comprises aplurality of angularly spaced arm members which extend outwardly fromthe hub.
 6. A marine propeller in accordance with clam 5 wherein the armmembers are attached to forward portions of the curved blades.
 7. Amarine propeller in accordance with claim 6 wherein the arm members arecocked at an angle so as to urge movement of water in the rearwarddirection.
 8. A marine propeller in accordance with claim 2 wherein: theshape of the hub corresponds to a pair of conical forms having a commonbase and pointing in opposite directions; each blade is in the form of acurved plate; the blades are positioned to encircle the rearward portionof the hub in an overlapping manner; and the support means comprises aplurality of angularly spaced arm members which extend outwardly fromthe hub and are attached to forward portions of the blades.